A common and repeated mistake has been seen in students’ work: students cancel out “a” for (a+b)/(a+c) to make the expression equal to b/c. They argue that if a(b+c)/a=b+c, why can’t they cancel out “a” for (a+b)/(a+c)? What’s up with that? How do you teach the related mathematics ideas so that students are able to understand the algebraic rules behind and help students make sense out of it? In this presentation, we will discuss the ways of students think and analyze why the mistakes happen.
Sliang@csusb.edu
What’s up with that?
A common and repeated mistake has been seen in students’ work: students cancel out “a” for (a+b)/(a+c) to make the expression equal to b/c. They argue that if a(b+c)/a=b+c, why can’t they cancel out “a” for (a+b)/(a+c)? What’s up with that? How do you teach the related mathematics ideas so that students are able to understand the algebraic rules behind and help students make sense out of it? In this presentation, we will discuss the ways of students think and analyze why the mistakes happen.